Method and device for sleep analysis

ABSTRACT

The various embodiments of the method of the present invention include a method to improving or expanding the capacity of a sleep analysis unit or laboratory, a method sleep analysis testing a patient admitted for diagnosis or treatment of another primary medical condition while being treated or diagnosed for that condition, a method of sleep analysis testing a patient that cannot be easily moved or treated in a sleep analysis unit or laboratory and other like methods.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority as a continuation of U.S. patentapplication Ser. No. 16/014,002 which was filed on Jun. 21, 2018, andwhich is a continuation of U.S. patent application Ser. No. 14/883,687which was filed on Oct. 15, 2015 and issued as U.S. Pat. No. 10,028,698on Jul. 24, 2018, and which is a continuation of U.S. patent applicationSer. No. 11/811,157, which was filed on Jun. 8, 2007 and issued as U.S.Pat. No. 9,202,008 on Dec. 1, 2015.

LICENSE RIGHTS FOR FEDERALLY-SPONSORED RESEARCH

The U.S. Government has a paid-up license in this invention and theright in limited circumstances to require the patent owner to licenseothers on reasonable terms provided for by the terms of grant numbers2R44NS042451-04 and 5R44NS042451-03 awarded by the National Institutesof Health.

BACKGROUND OF THE INVENTION

Nearly one in seven people in the United States suffer from some type ofchronic sleep disorder, and only 50% of people are estimated to get therecommended seven to eight hours of sleep each night. It is furtherestimated that sleep deprivation and its associated medical and socialcosts (loss of productivity, industrial accidents, etc.) exceed $150billion per year. Excessive sleepiness can deteriorate the quality oflife and is a major cause of morbidity and mortality due to its role inindustrial and transportation accidents. Sleepiness further hasundesirable effects on motor vehicle driving, employment, higher earningand job promotion opportunities, education, recreation, and personallife.

Primary sleep disorders affect approximately 50 million Americans of allages and include narcolepsy, restless legs/periodic leg movement,insomnia, and most commonly, obstructive sleep apnea (OSA). OSA'sprevalence in society is comparable with diabetes, asthma, and thelifetime risk of colon cancer. OSA is grossly under diagnosed; anestimated 80-90% of persons afflicted have not received a clinicaldiagnosis. Some medical conditions have been associated with increasedrisk for sleep disorders, specifically sleep-related breathingdisorders. Such conditions include cardiovascular disease such ashypertension, stroke, and congestive heart failure. Evidence indicatesthat treatment of the sleep-related breathing disorder can improvecardiac function in these patients. Similarly, evidence indicatessleep-related breathing disorders can increase the prevalence ofnocturnal cardiac arrhythmia development.

Sleeping disorders are currently diagnosed by two general methods.Subjective methods, such as the Epworth and Standford Sleepiness Scale,generally involve questionnaires that require patients to answer aseries of qualitative questions regarding their sleepiness during theday. With these subjective methods, however, it is found that thepatients usually underestimate their level of sleepiness or theydeliberately falsify their responses because of their concern regardingpunitive action or as an effort to obtain restricted stimulantmedication. The second group of methods uses physiological evaluations,such as all-night polysomnography to evaluate a patient's sleeparchitecture (e.g., obtaining respiratory disturbance index to diagnosesleep apnea). A polysomnogram (PSG) can also be followed by an all-daytest such as the Multiple Sleep Latency Test (MSLT) or its modifiedversion, the Maintenance of Wakefulness Test (MWT). The PSG typicallyrequires patients to spend the night in a sleep laboratory connected tomultiple sensors while they attempt to sleep.

Sleep laboratory studies require the patient to physically go to thesleep lab to be tested. These labs typically have a small number ofsleeping rooms containing all the necessary sleep study equipment. Theequipment from each room many times is wired to a central monitoringroom where a sleep technician collects and analyzes data from severalsubjects. Due to the limited capacity and a high volume of patientsrequiring sleep studies, many labs have unacceptable waiting lists.Additionally, many patients requiring sleep studies have related medicalconditions, such as severe cardiovascular disease, or are immobilemaking travel to a sleep lab difficult. As a result, many patients mustwait for an available appointment or improved health before alaboratory-based sleep study is possible. This delay in diagnosing thepatient's sleep disorder leads to a delay in treatment and an increasedrisk of developing a related medical condition.

Current methods attempting to conduct a sleep study at the patient'slocation have proved unsuccessful. Patients who are already ill orhospitalized cannot travel to a sleep lab, nor can a sleep test beconducted in an inpatient hospital room. Standard, and even specialized,hospital rooms are not equipped to conduct a sleep study. Facilities arenot frequently retrofitted with sleep study equipment due to the hugeexpense involved, particularly for limited use. Further, hospital roomsare crowded with other equipment, which makes adding bulky sleep studycarts infeasible. Similarly, few hospitals have space near patient roomsavailable for use as a monitoring room.

To address some of these concerns, methods have been developed toconduct unattended studies. An unattended sleep test does not requirethe step of transmitting the data to a monitoring location. Thesemethods have relied on equipment incapable of transmitting data duringthe sleep study, creating the unattended test. Such unattended tests,however, are plagued with signal failure. In one study involvingunattended PSG, data from over 23% of the patients were unusable due tomissing channels, even though a technician called the PSG recordingdevice every 30 minutes to check the quality of the recordings. Further,unattended tests do not resolve the problem of fitting a sleep cart intoa crowded patient room.

None of the current methods for conducting a sleep study outside a sleeplab allow transmission of the collected data during the test. All of thecurrent methods require the PSG data to be stored during the test andread only after the test has been completed. As such, the data cannot beperiodically or continuously checked for adequacy. Even if the data wereperiodically evaluated, the current methods do not use a step ofallowing a remote monitor to communicate with the subject to correct anysensor/signal problems. The current methods also do not include livevideo feeds that enable a remote monitor to visualize the subject duringthe sleep test. Moreover, the current methods make it extremelydifficult to conduct a full polysonnagram sleep study outside a sleeplab have enabled the entire sleep system to fit inside a crowdedhospital room.

It is therefore an object of the present invention to provide a methodof conducting a sleep analysis outside a sleep lab wherein the data istransmitted at substantially the same time it that is collected orcreated. It is another object of the present invention to provide amethod of conducting a sleep analysis outside the sleep lab that isremotely attended. It is another objective of the present invention toprovide a method of conducting a sleep analysis outside the sleep lab onsubjects who are already patients in a hospital room. It is stillanother objective of the present invention to provide a method ofconducting a sleep analysis with a small, lightweight data acquisitionsystem.

SUMMARY OF THE INVENTION

The present invention provides a method of conducting a sleep analysisby collecting physiologic and kinetic data from a subject with awireless data acquisition system, in a non-traditional location such asa hospital room, nursing home, a satellite hospital, hotel, and thelike. The sleep analysis, including clinical and research sleep studies,can be used in the diagnosis of sleeping disorders and other diseases orconditions with sleep signatures, such as Parkinson's, epilepsy, chronicheart failure, chronic obstructive pulmonary disorder, or otherneurological, cardiac, pulmonary, or muscular disorders.

The various embodiments of the method of the present invention include amethod to improving or expanding the capacity of a sleep analysis unitor laboratory, a method sleep analysis testing a patient admitted fordiagnosis or treatment of another primary medical condition while beingtreated or diagnosed for that condition, a method of sleep analysistesting a patient that cannot be easily moved or treated in a sleepanalysis unit or laboratory and other like methods.

The various embodiments of the present invention include a number ofsteps that enhance these methods over other methods presently used.These features available in various embodiments of the present inventionmay include, but are not necessarily limited to: a step for hooking upthe patient with the necessary sensors at a remote location, a step forcollecting multiple channels of data to evaluate a number ofphysiological, kinetic, and environmental features of the subject andsleeping location; a step for including a subject's body motion; a stepfor using removable memory for data buffering and storage; a step formovement artifact correction using video; a step for transmitting datawirelessly to a remote processing or monitoring station after a manualor automatic radio frequency (RF) sweep; a step for remotely checkingthe data for adequacy; a step for remotely monitoring the subject viastreaming data and audio/video for the duration of the test; a step forcommunicating with the subject during the test; and a step for adjustingelectrodes and other sensors during the test.

The software used in various steps of the present invention allows thepatient data acquisition system to perform a number of operations thatother systems cannot accomplish with the same type of hardware. The useof software filtering allows determination of airflow, tidal volume,ventilation rate, and snore detection from a single pressure transducer.The use of software also makes many of the video-related featurespossible. Software is used to synchronize video with the other signalsfor display. Software is also used to remove data artifacts created bysubject movement. The software corrects motion artifacts by using dataacquired from accelerometers and video.

The present invention preferably contains the step of wirelesslytransmitting data from the sensors for the sleep analysis atsubstantially the same time as it is collected. The patient wirelessacquisition system of the present invention is preferably small andcompact resulting in ease of use and improved patient mobility byeliminating the need to tether the patient.

The present invention may also include the step of transmitting data viaa wired network such as a dial-up modem, cellular networks, digitalsubscriber lines (DSL), cable broadband, fiber-optic lines, satellitecommunications, direct radio, infra-red links, and the like. The datacan be transmitted once, at multiple points during the test, orcontinuously. With continuous data transmission, the sleep test can beremotely monitored from anywhere around the world. The data furthermoremay be monitored by multiple viewing stations by methods including butnot limited to serial retransmission from one station to another, orsimultaneous transmission by 3-way or conference calling, broadcastingor the like. The data from the acquisition system is available forremote monitoring in real time, it can be saved and scored later, or maybe quantitatively analyzed and scored (even automatically) and thenviewed. With automatic or computer-assisted scoring, the software canalert a individual performing remote monitoring when a physiologicalevent (such as a drop in oxygen saturation) or a technological event(such as an electrode becoming disconnected) occurs.

Various embodiments of the present invention include the step ofapplying at least two sensors to the subject. The sensors can be appliedby a sleep technician, a clinician, a nurse or the like, at anylocation, preferably however, either at the facility which is being usedto expand the capacity of the sleep unit or laboratory, the facility towhich the patient was admitted for treatment of a primary medicalcondition, other than a sleeping disorder, or at the location of theimmobile patient such as a nursing home, extended care facility, or thelike. The method of the present invention further allows for hospitalin-patient sleep analysis where the patient is admitted for diagnosis ortreatment to a general medical or surgical unit, to a cardiac unit, to arespiratory unit, gastrointestinal unit, neurological unit, trauma unit,intensive care unit, materinity unit, pediatric unit, oncology unit,urology unit, psychiatric unit, hematology unit, infectuous diseaseunit, orthopedic unit, ear nose and throat unit, dermatology unit, orthe like

In one embodiment, the present invention includes a method of expandingthe capacity of a sleep analysis lab or unit comprising the steps ofapplying at least two sensors to a patient located in a facility remoteto a sleep analysis unit or lab; connecting the at least two sensors toa wireless data acquisition system; collecting data from the patientlocated in the remote facility while the patient is attempting to sleep;wirelessly transmitting the data at substantially the same time as it iscollected to the sleep analysis unit or lab or to a database accessibleto individuals from the sleep analysis unit or lab; and analysis of thedata by individuals from the sleep analysis unit or lab to determinewhether the patient suffers from a sleep disorder.

In another embodiment, the present invention includes a method of sleepanalysis or diagnosis on a patient admitted for diagnosis or treatmentfor other primary medical conditions comprising the steps of admitting apatient for diagnosis or treatment of a primary medical condition, otherthan a sleeping disorder, to a hospital room, other than one usedprimarily for sleep diagnosis or treatment; suspecting that the patientmay have a related or underlying sleep disorder; applying at least twosensors to the patient; connecting the at least two sensors to awireless data acquisition system; collecting data from the patientlocated in the hospital room while the patient is attempting to sleep;wirelessly transmitting the data at substantially the same time as it iscollected to a sleep analysis unit or lab or to a database accessible toindividuals from the sleep analysis unit or lab; and analysis of thedata by individuals from the sleep analysis unit or lab to determinewhether the patient suffers from a sleep disorder.

In still another embodiment, the present invention includes a method ofsleep analysis or diagnosis on a patient who cannot be moved to a sleepunit or lab, comprising the steps of suspecting that a patient may havea related or underlying sleep disorder; applying at least two sensors tothe patient; connecting the at least two sensors to a wireless dataacquisition system; collecting data from the patient at a location thatis not a sleep unit or lab while the patient is attempting to sleep;wirelessly transmitting the data at substantially the same time as it iscollected to a sleep analysis unit or lab or to a database accessible toindividuals from the sleep analysis unit or lab; and analysis of thedata by individuals from the sleep analysis unit or lab to determinewhether the patient suffers from a sleep disorder.

Additional features and advantages of the invention will be set forth inthe detailed description that follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription that follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary of theinvention, and are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate various embodimentsof the invention and together with the description serve to explain theprinciples and operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Block diagram of one embodiment of the present inventionincluding showing the steps of checking the adequacy of signals andcommunicating with the subject.

FIG. 2 Block diagram of another embodiment of the present invention.

FIG. 3 Block diagram of still another embodiment of the presentinvention.

FIG. 4 Signal flow diagram of one embodiment of the present inventionshowing the patient data acquisition system.

FIG. 5 Schematic representation of one embodiment of the presentinvention showing the remote data acquisition method.

FIG. 6 Schematic representation of one embodiment of the presentinvention used with a subject to acquire EEG signals from the subjectand then transmit them to the receiver and attached computer.

FIG. 7 Block diagram of one embodiment of the signal processing step ofthe present invention.

FIG. 8 Block diagram of one embodiment of the base station used in thepresent invention.

FIG. 9 Schematic representation of one embodiment of the presentinvention showing an patient data acquisition system of multipleinterface boxes used on a single subject, wherein the interface boxesare transmitting to a single receiver.

FIG. 10 Block diagram of one embodiment of the present invention showingthe motion artifact rejection process.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is related to a method of inpatient and remotesleep and signal analysis. The present invention is further related tothe devices used in executing the method. The present invention includesvarious embodiments of a method of inpatient and remote sleep analysis.These embodiments include but are not limited to one or more of thefollowing steps.

Various embodiments of the present invention include a step fordetermining whether the subject being analyzed for a sleep disordermaintained a normal sleeping pattern prior to the analysis. This stepcan be performed or accomplished a number of ways. In the simplest form,the subject or patient can be questioned regarding his or her previoussleep patterns. In a somewhat more complex form the subject can berequested to fill out a questionnaire, which then can be graded todetermine whether his or her previous sleep patterns where normal (orappeared normal). In an even more complex form the subject might undergoall night polysomnography to evaluate the subject's sleep architecture(e.g., obtaining respiratory disturbance index to diagnose sleep apnea).One of the objectives of this step is to ensure that the results of thesubject's or patient's brain wave analysis are not the result of oraffected by the subject's or patient's previous environmental factorsi.e., intentional lack of sleep, etc. It is clear that there arenumerous ways beyond those examples previously mentioned of determiningwhether the subject being analyzed maintained or thought they weremaintaining a normal sleeping pattern prior to analysis, therefore theexamples given above are included as exemplary rather than as alimitation, and those ways of determining whether the subject maintainedor thought they were maintaining a normal sleeping pattern known tothose skilled in the art are considered to be included in the presentinvention.

Various embodiments of the present invention include the step ofconducting an inpatient or remote sleep analysis that is attended from aremote location. Such remote attendance can be accomplished by anindividual in a remote location (a remote monitor) periodically orcontinuously viewing the data transmitted from the patient dataacquisition system, including signals from the sensors applied to thesubject, signals from the environmental sensors, and a pre-processedsignal or signals based at least in part on at least one of the sensors.Preferably, the data includes a video channel. Preferably, the remotemonitor is capable of communicating with the subject or patient, theirassistant, or another individual near the subject or patient. Suchcommunication allows the remote monitor to provide instructions to thesubject or patient, their assistant, or other individual near thesubject or patient, for example, to adjust a sensor, close windowblinds, remove a source of noise, or wake the subject. More preferably,the remote monitor is capable of two-way communication with the subject,subject's assistant, or other individual near the subject. Suchcommunication allows the subject, subject's assistant, or otherindividual close to the subject to ask the remote monitor questions, forexample, to clarify instructions. In many of the settings this otherindividual may be a nurse or trained technician at the hospital, nursinghome or skilled medical facility. In other settings, it can be any otherindividual trained in the placement and hookup of the sensors.

Various embodiments of the present invention include the step ofapplying at least two sensors to the subject or patient. The sensors canbe applied at any location. Preferably, the sensors are applied at thefacility such as the hospital where the patient is staying, and mostpreferably right in the patient's room. Care needs to be given whenapplying these sensors so as to not disturb or interfere with otherdiagnositic equipment, treatment devices or sensors on or in thevicinity of the patient. For example, in an intensive care unit orcardiac unit the patient may be monitored by EKG and have three or moreleads. Care must be taken not to interfere or disturb the electrodes orthe signal received. In addition, this method also provides for a stepin sharing common sensors. This step could include routing the data fromthese sensors through the patient data acquisition system or the datacan be combined with the other data run through the data acquisitionsystem down stream. For example, both the data from the patient dataacquisition system and EKG might be combined and synched for time in thedatabase, and this combined data used to make the sleep diagnosis oranalysis. Similarly, the sensors can be applied by a variety ofindividuals, including but not limited to a physician, nurse, sleeptechnician, or other healthcare professional. Although not aspreferable, the sensors could be applied by the patient or subject, orthe patient's or subject's spouse, friend, roommate, or other individualcapable of attaching the various sensors. More preferably, the sensorscould be applied by the subject or the subject's spouse, friend,roommate, or other individual capable of attaching the various sensorswith guidance and instruction. Such guidance and instruction can includestatic information such as pamphlets, audio recordings (on cassettes,compact discs, and the like), video recordings (on videocassettes,digital video discs, and the like), websites, and the like, as well asdynamic information such as direct real-time communication viatelephone, cell phone, videoconference, and the like.

The sensors that are used with various embodiments of the presentinvention are described herein but can also be any of those known tothose skilled in the art for the applications of this method. Thecollected physiological, kinetic, and environmental signals can beobtained by any method known in the art. Preferably, those sensorsinclude, but are not limited, to wet or dry electrodes, photodetectors,accelerometers, pneumotachometers, strain gauges, thermal sensors, pHsensors, chemical sensors, gas sensors (such as oxygen and carbondioxide sensors), transducers, piezo sensors, magnetometers, pressuresensors, static charge-sensitive beds, microphones, audio monitors,video monitors, and the like. The invention is envisioned to includethose sensors subsequently developed by those skilled in the art todetect these types of signals. For example, the sensors can be magneticsensors. Because electro-physiological signals are, in general,electrical currents that produce associated magnetic fields, the presentinvention further anticipates methods of sensing those magnetic fieldsto acquire the signal. For example, new magnetic sensors could collectbrain wave signals similar to those that can be obtained through atraditional electrode applied to the subject's scalp.

Various embodiments of the present invention include a step for applyingsensors to the subject. This step can be performed or accomplished in anumber of ways. In the simplest form, two sensors are applied to thesubject to measure a single channel of physiologic or kinetic data. In asomewhat more complex form, multiple sensors are applied to the subjectto collect data sufficient for a full PSG test. The preferred set ofsensors includes sensors for two EEG channels, two EOG channels, onechin EMG channel, one nasal airflow channel, one oral airflow channel,one ECG channel, one thoracic respiratory effort channel, one abdominalrespiratory effort channel, one pulse oximetry channel, and one shin orleg EMG channel. More preferably, the full set of PSG sensors isaugmented with at least one channel of body position (ex., anaccelerometer), one channel of video, and optionally one channel ofaudio. In an even more complex form, many sensors are applied to thesubject to collect full PSG data as well as additional physiological,kinetic, and environmental data. For example, additional EEG electrodesmay be applied to the subject to rule out seizure disorders, anesophageal pH sensor may be used to detect acid reflux, and a hygrometeror photometer may be used to detect ambient humidity or light,respectively.

Electro-physiological signals such as EEG, ECG, EMG, EOG,electroneurogram (ENG), electroretinogram (ERG), and the like can becollected via electrodes placed at one or several relevant locations onthe subject's body. For example when measuring brain wave or EEGsignals, electrodes may be placed at one or several locations on thesubject's scalp. In order to obtain a good electro-physiological signal,it is desirable to have low impedances for the electrodes. Typicalelectrodes placed on the skin may have an impedance in the range of from5 to 10 kΩ. It is in generally desirable to reduce such impedance levelsto below 2 kΩ. A conductive paste or gel may be applied to the electrodeto create a connection with an impedance below 2 kΩ. Alternatively or inconjunction with the conductive gel, a subject's skin may bemechanically abraded, the electrode may be amplified, or a dry electrodemay be used. Dry physiological recording electrodes of the typedescribed in U.S. Pat. No. 7,032,301 are herein incorporated byreference. Dry electrodes are advantageous because they use no gel thatcan dry out, skin abrasion or cleaning is unnecessary, and the electrodecan be applied in hairy areas such as the scalp. Additionally ifelectrodes are used as the sensors, preferably at least two electrodesare used for each channel of data—one signal electrode and one referenceelectrode. Optionally, a single reference electrode may be used for morethan one channel.

When electrodes are used to collect EEG or brain wave signals, commonlocations for the electrodes include frontal (F), parietal (P), mastoidprocess (A), central (C), and occipital (O). Preferably for the presentinvention, when electrodes are used to collect EEG or brain wave data,at least one electrode is placed in the occipital position andreferenced against an electrode placed on the mastoid process (A). Morepreferably, when electrodes are used to collect EEG or brain wave data,electrodes are placed to obtain a second channel of data from thecentral location. If further EEG or brain wave signal channels aredesired, the number of electrodes required will depend on whetherseparate reference electrodes or a single reference electrode is used.

If electrodes are used to collect cardiac signals using an ECG, they maybe placed at specific points on the subject's body. The ECG is used tomeasure the rate and regularity of heartbeats, determine the size andposition of the heart chambers assess any damage to the heart, anddiagnose sleeping disorders. An ECG is important as a tool to detect thecardiac abnormalities that can be associated with respiratory-relateddisorders.

As the heart undergoes depolarization and repolarization, electricalcurrents spread throughout the body because the body acts as a volumeconductor. The electrical currents generated by the heart are commonlymeasured by an array of twelve electrodes placed on the arms, legs, andchest. Although a full ECG test typically involves twelve electrodes,only two are required for many tests such as a sleep study. Whenelectrodes are used to collect ECG with the present invention,preferably only two electrodes are used. When two electrodes are used tocollect ECG, preferably one is placed on the subject's left-hand ribcageunder the armpit, and the other preferably on the right-hand shouldernear the clavicle bone. Optionally, a full set of twelve ECG electrodesmay be used, such as if the subject is suspected to have a cardiacdisorder. The specific location of each electrode on a subject's body iswell known to those skilled in the art and varies between bothindividuals and types of subjects. If electrodes are used to collectECG, preferably the electrode leads are connected to a device containedin the signal processing module of the patient data acquisition systemused in the present invention that measures potential differencesbetween selected electrodes to produce ECG tracings.

The two basic types of ECG leads are bipolar and unipolar. Bipolar leads(standard limb leads) have a single positive and a single negativeelectrode between which electrical potentials are measured. Unipolarleads (augmented leads and chest leads) have a single positive recordingelectrode and use a combination of the other electrodes to serve as acomposite negative electrode. Either type of lead is acceptable forcollecting ECG signals in the present invention.

Other sensors can be used to measure various parameters of a subject'srespirations. Measurement of airflow is preferably measured usingsensors or devices such as a pneumotachometer, strain gauges, thermalsensors, transducers, piezo sensors, magnetometers, pressure sensors,static charge-sensitive beds, and the like. These sensors or devicesalso preferably measure nasal pressure, respiratory inductanceplethysmography, thoracic impedance, expired carbon dioxide, trachealsound, snore sound, blood pressure and the like. Measurement ofrespiratory effort is preferably measured by a respiration belt,esophageal pressure, surface diaphragmatic EMG, and the like.Measurement of oxygenation and ventilation is preferably measured bypulse oximetry, transcutaneous oxygen monitoring, transcutaneous carbondioxide monitoring, expired end carbon dioxide monitoring, and the like.

One example of such a sensor for measuring respirations either directlyor indirectly is a respiration belt. Respiration belts can be used tomeasure a subject's abdominal and/or thoracic expansion over ameasurement time period. The respiration belts may contain a straingauge, a pressure transducer, or other sensors that can indirectlymeasure a subject's respirations and the variability of respirations byproviding a signal that correlates to the thoracic/abdominalexpansion/contractions of the subject's thoracic/abdominal cavity. Ifrespiration belts are used, they may be placed at one or severallocations on the subject's torso or in any other manner known to thoseskilled in the art. Preferably, when respiration belts are used, theyare positioned below the axilla and/or at the level of the umbilicus tomeasure rib cage and abdominal excursions. More preferably, at least twobelts are used, with one positioned at the axilla and the other at theumbilicus.

Another example of a sensor or method for measuring respirations eitherdirectly or indirectly is a nasal cannula or a facemask used to measurethe subject's respiratory airflow. Nasal or oral airflow can be measuredquantitatively and directly with a pneumotachograph consisting of apressure transducer connected to either a standard oxygen nasal cannulaplaced in the nose or a facemask over the subject's mouth and nose.Airflow can be estimated by measuring nasal or oral airway pressure thatdecreases during inspiration and increases during expiration.Inspiration and expiration produce fluctuations on the pressuretransducer's signal that is proportional to airflow. A single pressuretransducer can be used to measure the combined oral and nasal airflow.Alternatively, the oral and nasal components of these measurements canbe acquired directly through the use of at least two pressuretransducers, one transducer for each component. Preferably, the pressuretransducer(s) are internal to the interface box. If two transducers areused for nasal and oral measurements, preferably each has a separate airport into the interface box.

Software filtering can obtain “snore signals” from a single pressuretransducer signal by extracting the high frequency portion of thetransducer signal. This method eliminates the need for a separatesensor, such as a microphone or another transducer, and also reduces thesystem resources required to detect both snore and airflow. A modifiednasal cannula or facemask connected to a carbon dioxide or oxygen sensormay be used to measure respective concentrations of these gases. Inaddition, a variety of other sensors can be connected with either anasal cannula or facemask to measure a subject's respirations directlyor indirectly.

Still another example of a sensor or method of directly or indirectlymeasuring respirations of the subject is a pulse oximeter. The pulseoximeter can measure the oxygenation of the subject's blood by producinga source of light at two wavelengths (650 nm and 905, 910, or 940 nm).Hemoglobin partially absorbs the light by amounts that differ dependingon whether it is saturated or desaturated with oxygen. Calculating theabsorption at the two wavelengths leads to an estimate of the proportionof oxygenated hemoglobin. Preferably, pulse oximeters are placed on asubject's earlobe or fingertip. More preferably, the pulse oximeter isplaced on the subject's index finger. In one embodiment of the presentinvention, a pulse oximeter is built-in or hard-wired to the interfacebox. Alternatively, the pulse oximeter can be a separate unit incommunication with either the interface box or the base station viaeither a wired or wireless connection.

Kinetic data can be obtained by accelerometers placed on the subject.Alternatively, several accelerometers can be placed in various locationson the subject, for example on the wrists, torso, and legs. Theseaccelerometers can provide both motion and general position/orientationdata by measuring gravity. A video signal can also provide some kineticdata after processing. Alternatively, stereo video signals can providethree-dimensional position and motion information. Kinetic data includesbut is not limited to frequent tossing and turning indicative of anunsuitable mattress, excessive movement of bedding indicating unsuitablesleeping temperatures, and unusual movement patterns indicating pain.

While environmental data isn't as important as with in-home monitoring,environmental data can be collected by video cameras, microphones (todetect noise level, etc.), photodetectors, light meters, thermalsensors, particle detectors, chemical sensors, mold sensors, olfactorysensors, barometers, hygrometers, and the like. Environmental data canprovide insight into the subject's sleeping location and habits that isunavailable in the traditional laboratory setting. Environmental datacan indicate that the subject's sleeping location is a potential sourceof the subject's sleeping difficulty. By way of example, but notlimitation, environmental data can indicate that the subject's sleepinglocation has an unsuitable temperature, humidity, light level, noiselevel, or air quality. For example, these environmental conditions cancause sweating, shivering, sneezing, coughing, noise, and/or motion thatdisrupts the patient's sleep. The environmental sensors can be placedanywhere in the subject's sleeping location or on the subject, ifappropriate. Preferably, the environmental sensors are placed near, butnot necessarily on, the subject. Environmental data while not asimportant for these methods may have some application where the patientor subject is being diagnosed in an environment of long term care,particularly where these environmental factors may continue to affectthe patient or subject long after the diagnosis.

Other sensors can be used to measure various parameters of a subject'sphysiological, kinetic, or environmental conditions. These otherparameters are preferably measured using sensors or devices such as aphotodetectors, light meters, accelerometers, pneumotachometers, straingauges, thermal sensors, pH sensors, chemical sensors, transducers,piezo sensors, magnetometers, pressure sensors, static charge-sensitivebeds, audio monitors, microphones, reflective markers, video monitors,hygrometers, and the like. Because the system is programmable,potentially any transducer-type sensor that outputs an electrical signalcan be used with the system.

Various embodiments of the present invention include the step ofconnecting the applied sensors to a patient data acquisition system. Thesensors can be connected to the patient data acquisition system eitherbefore or after they are applied to the subject. As an example ofconnecting the sensors to the patient data acquisition system after thesensors are applied to the subject, a nurse can apply the sensors to thepatient or subject in the patient's room. The nurse or other caretakercan then connect the sensors with leads to the patient data acquisitionsystem. Alternatively, the sensors can be connected to the patient dataacquisition system and then applied to the patient, preferably in thepatient's room.

The sensors can be permanently hardwired to at least part of the patientdata acquisition system. More preferably, the sensors are connected toat least part of the patient data acquisition system via releasableconnector. The physiological sensors are generally hardwired(permanently or via releasable connector) to the patient dataacquisition system, but the ongoing evolution in wireless sensortechnology may allow sensors to contain transmitters. Optionally, suchsensors are wirelessly connected to the patient data acquisition system.As such, these sensors and the wireless connection method are consideredto be part of the present invention. With the advances inmicroelectromechanical systems (MEMS) sensor technology, the sensors mayhave integrated analog amplification, integrated A/D converters, andintegrated memory cells for calibration, allowing for some signalconditioning directly on the sensor before transmission.

Preferably, the sensors are all connected in the same way at the sametime, although this is certainly not required. It is possible, but lesspreferable, to connect the sensors with a combination of methods (i.e.,hardwired or wireless) at a combination of times (i.e., some beforeapplication to the subject, and some after application to the subject orpatient).

Preferably, at least two sensors are used to collect patient data; evenmore preferably, at least four sensors are used to collect patient data;still more preferably, at least six sensors are used to collect patientdata; still more preferably, at least eight sensors are used to collectpatient data; still more preferably at least ten sensors are used tocollect patient data; still more preferably, at least fifteen sensorsare used to collect patient data; still more preferably, at least twentysensors are used to collect patient data; and most preferably,twenty-four sensors are used to collect patient data. Preferably atleast one sensor is used to collect environmental data; more preferably,at least two sensors are used to collect environmental data; still morepreferably at least four sensors are used to collect environmental data;and most preferably at least six sensors are used to collectenvironmental data.

Various embodiments of the present invention use a patient dataacquisition system. The patient data acquisition system is preferablyportable. By portable, it is meant, among other things, that the deviceis capable of being transported relatively easily. Relative ease intransport means that the device is easily worn and carried, generally ina carrying case, to the point of use or application and then worn by thepatient or subject without significantly affecting any range of motion.Furthermore, any components of the patient data acquisition system thatare attached to or worn by the subject, such as the sensors and patientinterface box, should also be lightweight. Preferably, thesepatient-contacting components of the device (including the sensors andthe patient interface box) weigh less than about 10 lbs., morepreferably less than about 7.5 lbs., even more preferably less thanabout 5 lbs., and most preferably less than about 2.5 lbs. Thus, thepatient-contacting components of the device preferably arebattery-powered and use a data storage memory card and/or wirelesstransmission of data, allowing the subject to be untethered.Furthermore, the entire patient data acquisition system (including thepatient-contacting components as well as any environmental sensors, basestation, or other components) preferably should be relativelylightweight. By relatively lightweight, it is meant preferably theentire patient data acquisition system, including all components such asany processors, computers, video screens, cameras, and the likepreferably weigh less in total than about 20 lbs., more preferably lessthan about 15 lbs., and most preferably less than about 10 lbs. Thispatient data acquisition system preferably can fit in a reasonably sizedcarrying case so the patient or assistant can easily transport thesystem. By being lightweight, wireless and compact, the device shouldgain greater acceptance for use by the patient or subject.

Various embodiments of the present invention use a patient dataacquisition system capable of receiving signals from the sensors appliedto the subject and capable of retransmitting the signals or transmittinganother signal based at least in part on at least one of the signals. Inits simplest form, the patient data acquisition system preferably shouldinterface with the sensors applied to the subject and retransmit thesignals from the sensors. Preferably, the patient data acquisitionsystem wirelessly transmits the signals from the sensors. Optionally,the patient data acquisition system also pre-processes the signals fromthe sensors and transmits the pre-processed signals. Further optionally,the data acquisition is also capable of storing the signals from thesensors and/or any pre-processed signals.

Optionally, the patient data acquisition system can be a single boxcontaining a sensor interface module, a pre-processor module, and atransmitter module. Further optionally, the patient data acquisitionsystem could consist of several boxes that communicate with each other,each box containing one or more modules. For example, the dataacquisition could consist of (a) a patient interface box containing asensor interface module, a pre-processor, a transmitter, and a receiver;and (b) a base station box containing a second pre-processor, atransmitter, and a receiver. In this example, the transmitter andreceiver of the patient box are used to communicate with the basestation box. The transmitter and receiver of the base station box areused to both communicate with the patient box and a remote monitoringstation, remote analysis station, remote data storage station, and thelike. Similarly, the data acquisition could consist of (a) a patientinterface box containing a sensor interface module, a transmitter, and areceiver; (b) a processor box containing a pre-processor, a transmitter,and a receiver; and (c) a base station box containing only a receiverand a transmitter. In these configurations, it is not necessary for thetransmitters to be of the same type. For example, the transmitter in thepatient interface box can be a wired or Bluetooth transmitter, and thetransmitter in the base station box can be a WiFi or IEEE 802.11transmitter designed to establish connections over larger distances. Thepatient data acquisition interface box further is preferably capable ofbeing reprogrammed remotely.

Various embodiments of the present invention use a patient dataacquisition system capable of storing and/or retransmitting the signalsfrom the sensors or storing and/or transmitting another signal based atleast in part on at least one of the signals. The patient dataacquisition system can be programmed and reprogrammed to send all signaldata to the removable memory, to transmit all data, or to both transmitall data and send a copy of the data to the removable memory. When thepatient data acquisition system is programmed to store a signal orpre-processed signal, the signals from the sensors can be saved on amedium in order to be retrieved and analyzed at a later date. Media onwhich data can be saved include, but are not limited to chart recorders,hard drive, floppy disks, computer networks, optical storage,solid-state memory, magnetic tape, punch cards, etc. Preferably, dataare stored on removable memory. For both storing and transmitting orretransmitting data, flexible use of removable memory can either buffersignal data or store the data for later transmission. Preferably,nonvolatile removable memory can be used to customize the system'sbuffering capacity and completely store the data.

In the patient data acquisition system when transmitting the data, theremovable memory acts as a buffer. In this situation, if the patientdata acquisition system loses its connection with the receiving station,the patient data acquisition system will temporarily store the data inthe removable memory until the connection is restored and datatransmission can resume and catch up in real time. In the event of alarger transmission failure, the patient data acquisition system can beconfigured to send all data to the removable memory for storage, thenthe system does not transmit any information at that time. In thissituation, the data stored on the removable memory can be retrieved byeither transmission from the patient data acquisition system, or byremoving the memory for direct reading.

The method of directly reading will depend on the format of theremovable memory. Preferably the removable memory is easily removableand can be removed instantly or almost instantly without tools. Thememory is preferably in the form of a card and most preferably in theform of a small easily removable card with an imprint (or upper or lowersurface) area of less than about two sq. in. If the removable memory isbeing used for data storage, preferably it can write data as fast as itis produced by the system, and it possesses enough memory capacity forthe duration of the test. These demands will obviously depend on thetype of test being conducted, tests requiring more sensors, highersampling rates, and longer duration of testing will require faster writespeeds and larger data capacity. The type of removable memory used canbe almost any type that meets the needs of the test being applied. Someexamples of the possible types of memory that could be used include butare not limited to Flash Memory such as CompactFlash, SmartMedia,Miniature Card, SD/MMC, Memory Stick, or xD-Picture Card. Alternatively,a portable hard drive, CD-RW burner, DVD-RW burner or other data storageperipheral could be used. Preferably, a SD/MMC—flash memory card is useddue to its small size. A PCMCIA card is least preferable because of thesize and weight.

When the patient data acquisition system is programmed to retransmit thesignals from the sensors, preferably the patient data acquisition systemtransmits the signals to a processor for analysis. More preferably, thepatient data acquisition system immediately retransmits the signals to aprocessor for analysis. Optionally, the patient data acquisition systemreceives the signals from one or more of the aforementioned sensors andstores the signals for later transmission and analysis. Optionally, thepatient data acquisition system both stores the signals and immediatelyretransmits the signals.

When the patient data acquisition system is programmed to retransmit thesignals from the sensors or transmit a signal based at least in part onthe signal from the sensors (collectively “to transmit” in thissection), the patient data acquisition system preferably transmits thedata through a wireless system, or some combination or a wireless andtethered system. When the system is configured to transmit data,preferably the data transmission step utilizes a two-way(bi-directional) data transmission. Using two-way data transmissionsignificantly increases data integrity. By transmitting redundantinformation, the receiver (the processor, monitoring station, or thelike) can recognize errors and request a renewed transmission of thedata. In the presence of excessive transmission problems, such astransmission over excessive distances or obstacles absorbing thesignals, the patient data acquisition system can control the datatransmission or independently manipulate the data. With control of datatransmission it is also possible to control or re-set the parameters ofthe system, e.g., changing the transmission channel or encryptionscheme. For example, if the signal transmitted is superimposed by othersources of interference, the receiving component could secure a flawlesstransmission by changing the channel. Another example would be if thetransmitted signal is too weak, the receiving component could transmit acommand to increase the transmitting power. Still another example wouldbe for the receiving component to change the data format of thetransmission, e.g., in order to increase the redundant information inthe data flow. Increased redundancy allows easier detection andcorrection of transmission errors. In this way, safe data transmissionsare possible even with the poorest transmission qualities. Thistechnique opens a simple way to reduce the transmission powerrequirements, thereby reducing the energy requirements and providinglonger battery life. Another advantage of a bi-directional digital datatransmission lies in the possibility of transmitting test codes in orderto filter out external interferences, for example, refraction or scatterfrom the transmission current. In this way, it is possible toreconstruct falsely transmitted data.

Preferably, the patient data acquisition system has a battery life of atleast four hours, more preferably of at least eight hours, still morepreferably at least twelve hours, even more preferably at least sixteenhours, and most preferably of at least twenty-four hours.

All of the preferable embodiments of the methods of the presentinvention employ a wireless patient data acquisition system. Thiswireless patient data acquisition system consists of several components,each wirelessly connected. Data is collected from the sensors describedabove by a patient interface box. The patient interface box thenwirelessly transmits the data preferably to a separate signalpre-processing module, which then wirelessly transmits the pre-processedsignal to a receiver. Alternatively, the patient interface box processesthe signal and then directly transmits the processed signal directly toa receiver or database using wireless technology. Further alternatively,the patient interface box wirelessly transmits the signals to thereceiver, which then pre-processes the signal. Preferably, the wirelesstechnology used by the patient data acquisition system components isradio frequency based. Most preferably, the wireless technology isdigital radio frequency based. The signals from the sensors and/or thepre-processed signals are transmitted wirelessly to a receiver, whichcan be a base station, a transceiver hooked to a computer, a personaldigital assistant (PDA), a cellular phone, a wireless network, or thelike. Most preferably, the physiological signals are transmittedwirelessly in digital format to a receiver.

Wireless signals between the wireless patient data acquisition systemcomponents are both received and transmitted via frequencies preferablyless than about 2.0 GHz. More preferably, the frequencies are primarily902-928 MHz, but Wireless Medical Telemetry Bands (WMTS), 608-614 MHz,1395-1400 MHz, or 1429-1432 MHz can also be used. The present inventionmay also use other less preferable frequencies above 2.0 GHz for datatransmission, including but not limited to such standards as Bluetooth,WiFi, IEEE 802.11, and the like.

When a component of the wireless patient data acquisition system isconfigured to wirelessly transmit data, it is preferably capable ofconducting a RF sweep to detect an occupied frequency or possibleinterference. The system is capable of operating in either “manual” or“automatic” mode. In the manual mode, the system conducts an RF sweepand displays the results of the scan to the system monitor. The user ofthe system can then manually choose which frequency or channel to usefor data transmission. In automatic mode, the system conducts a RF sweepand automatically chooses which frequencies to use for datatransmission. The system also preferably employs a form of frequencyhopping to avoid interference and improve security. The system scans theRF environment then picks a channel over which to transmit based on theamount of interference occurring in the frequency range.

The receiver (base station, remote communication station, or the like)of various embodiments of the wireless patient data acquisition systemcan be any device known to receive RF transmissions used by thoseskilled in the art to receive transmissions of data. By way of examplebut not limitation, the receiver can include a communications device forrelaying the transmission, a communications device for re-processing thetransmission, a communications device for re-processing the transmissionthen relaying it to another remote communication station, a computerwith wireless capabilities, a PDA with wireless capabilities, aprocessor, a processor with display capabilities, and combinations ofthese devices. Optionally, the receiver can further transmit data toanother device and/or back. Further optionally, two different receiverscan be used, one for receiving transmitted data and another for sendingdata. For example, with the wireless patient data acquisition systemused in the present invention, the receiver can be a wireless routerthat establishes a broadband Internet connection and transmits thephysiological signal to a remote Internet site for analysis, preferablyby the subject's physician or another clinician. Other examples of areceiver are a PDA, computer, or cell phone that receives the datatransmission, optionally re-processes the information, and re-transmitsthe information via cell towers, land phone lines, or cable to a remoteprocessor or remote monitoring site for analysis. Other examples of areceiver are a computer or processor that receives the data transmissionand displays the data or records it on some recording medium that can bedisplayed or transferred for analysis at a later time.

The preferred embodiment of secure data transmission that is compatiblewith HIPAA and HCFA guidelines will be implemented using a virtualprivate network. More preferably, the virtual private network will beimplemented using a specialized security appliance, such as the PIX506E, from Cisco Systems, Inc, capable of implementing IKE and IPSec VPNstandards using data encryption techniques such as 168-bit 3DES, 256-bitAES, and the like. Still more preferably, secure transmission will beprovided by a 3^(rd) party service provider or by the healthcarefacility's information technology department. The system will offerconfiguration management facilities to allow it to adapt to changingguidelines for protecting patient health information (PHI).

Preferably, the patient data acquisition system retransmits the signalsfrom the sensors applied to the subject (or patient) or transmits asignal based at least in part on at least one of the physiological,kinetic, or environmental signals at substantially a same time as thesignal is received or generated. At substantially the same timepreferably means within approximately one hour. More preferably, atsubstantially the same time means within thirty minutes. Still morepreferably, at substantially the same time means within ten minutes.Still more preferably, at substantially the same time means withinapproximately one minute. Still more preferably, at substantially thesame time means within milliseconds of when the signal is received orgenerated. Most preferably, a substantially same time means that thesignal is transmitted or retransmitted at a nearly instantaneous time asit is received or generated. Transmitting or retransmitting the signalat substantially a same time allows the physician or monitoring serviceto review the subject's physiological and kinetic signals and theenvironmental signals and if necessary to make a determination, whichcould include modifying the patient's treatment protocols or asking thesubject (patient) or caregiver to adjust the sensors.

Various embodiments of the present invention include a step ofmonitoring a patient from a separate monitoring location. Datatransmitted in a remote monitoring application may include, but are notlimited to, physiological data, kinetic data, environmental data, audio,and/or video recording. It is preferable that both audio and videocommunications be components of the envisioned system in order toprovide interaction between patient and caregiver.

The envisioned remote monitoring step will require data processing,storage, and/or transmission. This step may be completed or accomplishedin one or more modules of the patient data acquisition system. Thepreferred embodiment realizes the remote system as two separatecomponents with a patient interface module that can collect, digitize,store, and transmit data to a base station module that can store,process, compress, encrypt, and transmit data to a remote monitoringlocation.

Preferably, the data is transmitted from a base station to a database orremote monitoring location with a wireless module or card through acellular service provider. Also preferably, the data is transmitted froma base station to a database or remote monitoring location through awireless network or a wired local area network. The envisioned remotemonitoring application may allow for multiple remote monitoringlocations anywhere in the world. For instance, for an inpatient a nursein for example a general surgical unit may apply the sensors and thenmonitor the data for adequate sensor placement while at the same time aremote sleep technician monitors the data for adequate sensor placementand to score the analysis. Remote data collection to monitoring stationconfigurations may include, but are not limited to one-to-one,one-to-many, many-to-one, or many-to-many. The envisioned system mayinclude a central server, or group of servers that can collect data fromone or more remote sites and offer delivery to multiple viewing clients.

It is preferable that the remote monitoring application employ awireless network link between the patient and the sleep unit orlaboratory such as a cellular wireless network. Other wirelesstechniques include but are not limited to satellite communications,direct radio, infrared links, and the like. Data transmission through awired network such as dial-up modem, digital subscriber line (DSL), orfiber-optic, while less preferable, can also be used. Bandwidthmanagement facilities will be employed to facilitate remote monitoringin low-speed communication networks. Several data compression techniquesare envisioned to maximize system utilization in low-bandwidthenvironments. It is also preferably that the patient or subject is nottethered to any device other than a small, portable patient dataacquisition box that can be held or attached easily to the patient orsubject.

Data compression using lossless encoding techniques can provide basicthroughput optimization, while certain lossy encoding techniques willoffer far greater throughput while still providing useful data. Lossyencoding techniques may include but are not limited to decimation, ortransmission of a compressed image of the data. The preferred method forencoding will include special processing from the transmitter that willpreprocess the data according to user-selectable options, such asdigital filtering, and take into the account the desired visualrepresentation of that information, such as pixel height and targetimage width. Facilities can be made within the system to control theencoding in order to optimize utilization on any given network. Controlover the encoding methods may include, but is not limited to selectionof a subset of the entire set of signals, target image size, anddecimation ratio.

Data encryption can be applied to secure data transmissions over anynetwork. Encryption methods may include but are not limited to simpleobfuscation and sophisticated ciphers.

The preferred embodiment of the aforementioned remote monitoring system(a form of the patient data acquisition system) will consist of severalsystem modules. A patient interface module will collect physiologicaland kinetic data and transmit them to a base station module. The basestation module will receive the physiological and kinetic data from thepatient module, and will also directly connect to the environmentalsensors. The base station module will consist of an embedded computerequipped with a cellular wireless data/voice card and a night-visionvideo acquisition system. The embedded computer will collect, analyze,compress, and encrypt the data and relay them to one or more viewingcaregivers. The remote monitoring systems will broadcast theirdynamically assigned IP addresses to a dedicated address server, whichwill be used for lookup by the viewing caregivers. Computer softwareused by caregivers will enumerate each remote monitoring system in thefield using the aforementioned address server and allow caregivers toselect one or more for monitoring. The software will have the ability tocontrol data acquisition including start and stop of acquisition, aswell as system reconfiguration.

The software will also provide real-time control over the display ofdata including page width, amplitude, color, montage, and the like. Thesoftware will also provide both real-time video and audio communicationwith the patient using dual services from the cellular card. Video willpreferably be transmitted through the data connection, and audio willpreferably be transmitted through the voice connection.

Signal quality of the signals from all the sensors can be affected bythe posture and movement of the subject. For methods of the presentinvention, it is important to reduce motion artifacts from the sensorplacement. Errors in the form of noise can occur when biopotential dataacquisition is performed on a subject. For example, a motion artifact isnoise that is introduced to a biopotential signal via motion of anelectrode placed on the skin of a subject. A motion artifact can also becaused by bending of the electrical leads connected to any sensor. Thepresence of motion artifacts can result in misdiagnosis, prolongprocedure duration and can lead to delayed or inappropriate treatmentdecisions. Thus, it is imperative to remove motion artifact from thebiopotential signal to prevent these problems from occurring duringtreatment.

The present method of collecting signals from a subject includes amethod for reducing motion artifacts. Preferably, the electrode sensorsare used with conductive gels or adhesives. More preferably, dryelectrodes are used with or without conductive gels or adhesives. Stillmore preferably, the device's firmware and/or software uses body motioninformation for artifact correction. Most preferably, a combination ofthe above methods is used.

The most common methods for reducing the effects of motion artifacts insensors such as electrodes have focused on skin deformation. Thesemethods include removing the upper epidermal layer of the skin byabrasion, puncturing the skin near the electrode, or measuring skinstretch at the electrode site. The methods for skin abrasion ensure goodelectrical contact between the electrode and the subject's skin. In thismethod, an abrasive pad is mechanically rotated on the skin to abradethe skin surface before electrode placement. Moreover, medicalelectrodes have been used with an abrading member to prepare the skinafter application of the electrode whereby an applicator gun rotates theabrading member. Methods of skin preparation that abrade the skin with abundle of fibers have also been disclosed. The methods discussed aboveprovide a light abrasion of the skin to reduce the electrical potentialand minimize the impedance of the skin, thereby reducing motionartifacts.

Skin abrasion methods can cause unnecessary subject discomfort, prolongprocedure preparation time and can vary based on operator experience.Furthermore, skin abrasions methods can lead to infection, and do notprovide an effective solution to long term monitoring. Dry physiologicalrecording electrodes could be used as an alternative to gel electrodes.Dry physiological recording electrodes of the type described in U.S.Pat. No. 7,032,301 are herein incorporated by reference. Dryphysiological electrodes do not require any of the skin abrasiontechniques mentioned above and are less likely to produce motionartifacts in general.

Although the above-mentioned methods reduce motion artifacts, they donot completely eliminate them. The invention preferably incorporates astep to more completely remove motion and other artifacts by firmwareand/or software correction that utilizes information collectedpreferably from a sensor or device to detect body motion, and morepreferably from an accelerometer. In certain embodiments of the presentinvention, a 3-D accelerometer is directly connected to the patient dataacquisition system. The patient data acquisition system receives signalinputs from the accelerometer and at least one set of otherphysiological or kinetic signals. The microprocessor applies particulartests and algorithms comparing the two signal sets to correct any motionartifacts that have occurred. The processor in one embodiment applies atime synchronization test, which compares the at least one set ofphysiological or kinetic signal data to the accelerometer signal datasynchronized in time to detect motion artifacts and then remove thoseartifacts. Alternatively, the processor may apply a more complicatedfrequency analysis. Frequency analysis preferably in the form of waveletanalysis can be applied to the accelerometer and at least one set ofphysiological or kinetic signals to yield artifact detection. Yetanother alternative is to create a neural net model to improve artifactdetection and rejection. This allows for the system to be taught overtime to detect and correct motion artifacts that typically occur duringa test study. The above examples are only examples of possibleembodiments of the present invention and are not limitations. Theaccelerometer data need not be analyzed before wireless transmission; itcould be transmitted analyzed by a base station, computer, or the likeafter transmission. As should be obvious to those skilled in the art, a2-D accelerometer or an appropriate array of accelerometers could alsobe used. Gyroscopes could be used as well for these purposes.

Sensors can be used to detect motion of the subject's or patient's bodyor a portion of their body. The motion information can then be used todetect the posture and movement of the patient or subject and to correctfor error in the form of noise or motion artifact in the other sensorchannels. To detect motion, various embodiments of the present inventioninclude sensors, devices, and methods of determining the posture andmovement of the subject. This information can be used when analyzing thephysiological signals. The posture and movement of the subject ispreferably determined by signals received from an accelerometer or anarray of two or more accelerometers. Accelerometers are known in the artand are suitable for use as motion-monitoring units. Various other typesof sensors can be additionally or alternatively used to sense thecriteria (e.g., vibration, force, speed, and direction) used indetermining motion. For particularly low power designs, the one or moresensors used can be largely mechanical.

Body movement of the subject will result in a high amplitude signal fromthe accelerometer. The patient data acquisition system can also monitorthe sensor signals for any indication that the subject has moved, forexample from a supine position to an upright position. For example, theintegrated velocity signal computed from the vertical accelerationcomponent of the sensor data can be used to determine that the subjecthas just stood up from a chair or sat up in bed. A sudden change in thevertical signal, particularly following a prolonged period with littleactivity while the subject is sleeping or resting, confirms that aposture-changing event occurred.

In addition, a video camera can be used to detect subject movement andposition, and the information then used to correct any artifacts thatmay have arisen from such movement. Preferably, the camera is a digitalcamera. More preferably, the camera is a wireless digital camera. Stillmore preferably, the camera is a wireless digital infrared camera.Preferably, the video acquired from the camera is processed so that thesubject's movement and position are isolated from other information inthe video. The movement and position data that are acquired from thevideo is then preferably analyzed by software algorithms. This analysiswill yield the information needed to make artifact corrections of thephysiological signals.

One specific embodiment of the present invention using video patient orsubject movement detection involves the use of specially markedelectrodes. The electrodes can be any appropriate electrode known in theart. The only change to the electrode is that they preferably havepredetermined high contrast marks on them to make them more visible tothe video camera. These marking could be manufactured into theelectrodes or simply be a sticker that is placed on the back of theelectrodes. These markings enable the video system to accuratelydistinguish the electrodes from the rest of the video image. Using themarkers on each visible electrode, the system can calculate of themovement of each individual electrode, thus allowing for more accurateartifact correction.

In another specific embodiment of the invention, the system can detectsubject movement by monitoring the actual movement of the patient's orsubject's body. Software is applied to the video that first isolates theposition of the subject's body, including limbs, and then continues tomonitor the motion of the subject.

There are numerous advantages to using video over other means ofartifact detection and correction. Foremost, video allows for thecalculation of movement artifacts from each individual electrode withoutthe need for accelerometers. This makes the use of video very costeffective in relation to other available methods. The video also can beused in conjunction with the accelerometer data to correct for motionartifacts, thus increasing the precision and accuracy of the system'smotion artifact correction capabilities.

Various embodiments of the present invention include the step ofpre-processing the signals received from the sensors attached to thepatient or subject. The processor or pre-processor of variousembodiments of the present invention can be independent, a part of theinterface box, or a part of the base station. Optionally, pre-processingcan correct artifacts, derive a snore signal, filter a signal, orcompress and/or encrypt the data for transmission, each as describedabove. Preferably, the preprocessing step corrects for artifacts presentin the sensor signals.

Various embodiments of the present invention include the step ofanalyzing the received signals to determine if the patient has asleeping disorder. This step can be performed or accomplished a numberof ways. In one form, a sleep technician or other trained individualscores the sleep test in accordance with Rechtschaffen and Kales (R&K)criteria. Another form uses a standard MSLT analysis. Still another forminvolves automatic or computer-assisted scoring of the data. Theanalysis step can include a full R&K score, or specific features can betargeted. For example, in cases of suspected sleep-related breathingdisorders, the analysis can focus on detecting and classifyingrespiratory events. Any analysis method used to diagnose sleepingdisorders (including but not limited to insomnia, excessive daytimesleepiness, parasomnias, restless leg syndrome, periodic limb movementdisorder, and sleep-disordered breathing such as apneas) based onphysiological and/or kinetic data collected while the subject attemptsto sleep is an appropriate means of completing this step. Analysis canalso include subjective information from the subject, such as thesubject's response to questions. Such questions include, but are notlimited to, standard subjective questionnaires such as the Epworth andStandford Sleepiness Scale, and asking if the subject slept well.

The analysis can occur after receipt of the entire data set. Morepreferably, the analysis can take place in near-real time as the dataare received. Still more preferably, the analysis is computer-assistedand takes place in near-real time. Alternatively, the data can bepartially analyzed, with or without computer assistance, in near-realtime, and then fully analyzed at a later time. If at least some of theanalysis is conducted in near-real time with computer assistance, theanalysis software can provide an alert signal to draw attention to aphysiological or technological event. Physiological events include, butare not limited to, changes in blood oxygen saturation, changes inpulse, changes in sleep stage, and subject movement, such as leaving thebed. Technological events include, but are not limited to, movement of asensor, changes in electrode impedance, or loss of data. Once alerted toa physiological or technological event, the remote monitor can takeaction, including but not limited to communicating with the subject toaddress a problem, making a note of the event, conducting more detailedanalysis, altering the test parameters, or alerting another individualsuch as a physician, nurse, sleep technician, or the subject'sassistant.

Various embodiments of the present invention include the step ofevaluating the received signals to determine if they are adequate forlater analysis. This step can be performed or accomplished a number ofways. In the simplest form, the signal can be evaluated once just priorto the start of the sleep study. In another form, the signal isevaluated periodically during the study to determine its quality.Preferably, the signal(s) are evaluated both at the start of the studyand periodically during the study. Most preferably, the signals areevaluated at the beginning of the study and continuously during thestudy. If the signals are evaluated for adequacy, preferably the subjectcan be contacted to adjust the sensor as necessary. In this way,corrective action can adjust an inadequate signal to increase the valueof the sleep study data and enable later analysis. For example withelectrodes an impedance check can be performed.

The patient testing in the various embodiments of the present inventionis not performed in a sleep unit or laboratory. The result of this isthat these methods expand the capabilities of existing sleep units orlaboratories. A patient can be testing by an new or existing sleep unitor laboratory at another hospital, at a satellite hospital, at the samehospital but in a different unit, at a nursing home, at a clinic, andthe like. Because of the portability and size of the equipment, thesemethods of sleep analysis can be performed without the need forreconfiguring the room the patient is tested in. Because of thecapability of the equipment, this equipment can perform dual purposes oruses such as doing a sleep analysis and EKG simultaneously.

While the equipment used in such methods can be used in a hospital unitadjacent to the sleep unit or laboratory, due to the equipment's robustnature these methods are preferably performed over greater distances.Preferably, the testing location is another hospital, facility, nursinghome, clinic or the like. Preferably, the testing location is at least 1mile from the remote location receiving the data; more preferably, thetesting location is at least 5 miles from the remote location receivingthe data; even more preferably, the testing location is at least twentymiles from the remote location receiving the data; still morepreferably, the testing location is at least fifty miles from the remotelocation receiving the data; still even more preferably, the testinglocation is at least two hundred-fifty miles from the remote locationreceiving the data; more preferably, the testing location is in adifferent state from the remote location receiving the data; and mostpreferably, the testing location is in a different country from theremote location receiving the data.

By transmitting the data wirelessly in this application it is meant thatthe data at least in part of the data transfer process is transmittedwirelessly. This means for example that the data may be transmittedwirelessly from the patient data acquisition box to the base station andthen sent via wireless cellular card, internet, through the testingfacilities LAN, or any other communication system. This also means forexample that the data may be transmitted directly from the patient dataacquisition box through a wireless cellular card then over the internetto a database which distributes the data over a hardwired system to thesleep unit or lab. This also means for example that the data may betransmitted directly from the patient data acquisition box with awireless WIFI card directly to a wireless network then over the internetto a processor which retransmits the processed data to the sleep unit orlaboratory. Preferably, the patient data acquisition box, however, needsto wirelessly transmit the data. This allows for a simplified patienthookup and improved patient mobility.

The data collected for the sleep analysis conducted under the variousmethods of the present invention can be viewed by any number of medicalpersonnel and the patient themselves, if appropriate. Preferably, thedata is available to a sleep technician, to a doctor making theanalysis/diagnosis based on the data, and others involved in thesemethods. This data can be reviewed at multiple locations including butnot limited to the doctor's home or office, or anywhere else the doctoror other individuals associated with the analysis/diagnosis have accessto the internet or a intranet.

FIG. 1 is a block diagram of one embodiment of the sleep analysis methodof the present invention showing, among other things, the steps ofchecking the adequacy of signals and communicating with the patient orthe patient's caregiver. In this embodiment, a physician, nurse,technician, or the like applies sensors to the patient 4 at a locationthat is not a sleep unit or laboratory. Before or after the sensors areapplied to the patient, they are connected to a wireless dataacquisition system 6. The wireless data acquisition system collects somedata from the sensors and transmits the data to a remote station 8. Atthe remote station, a remote monitor checks the signals for adequacy 10.If the signal is not adequate for later analysis 12, the remote monitorcommunicates with the subject or the subject's caregiver to adjust thesensor 14. After the sensor is adjusted according to instructions fromthe remote monitor, the wireless data acquisition system collects andtransmits more data to the remote monitoring station 8. The signal fromthe adjusted sensor is checked for adequacy 10. The signal check loop 8,10, 12, 14 is repeated until the signals from all sensors are adequatefor later analysis.

After the wireless data acquisition system is sending adequate signals12, the sleep test is started by collecting data while the subjectattempts to sleep 16. During the test, data is collected and wirelesslytransmitted to the remote monitoring station 18. Based on thetransmitted data, a sleep analysis is performed and the patient isdiagnosed 20.

FIG. 2 is a block diagram of one embodiment of the sleep analysis methodof the present invention showing, among other things, the steps ofadmitting a patient for diagnosis or treatment of another medicalcondition and suspecting that the patient has a related or underlyingsleep disorder. In this embodiment, a patient is admitted to a hospitalroom that is not primarily used for sleep analysis for a primary medicalcondition that is not a sleep disorder 300. While the patient is in thehospital, the patient's caregivers suspect that the patient may have anunderlying or related sleep disorder 304. A physician, nurse,technician, or the like applies sensors to the patient 308 in thepatient's hospital room. Before or after the sensors are applied to thepatient, they are connected to a wireless data acquisition system 312.The sleep test is started by collecting data while the subject attemptsto sleep in the subject's hospital room 316. During the test, data iscollected and wirelessly transmitted to a remote sleep unit or lab ordatabase accessible to a sleep unit or lab 320. Based on the transmitteddata, a sleep analysis is performed and the patient is diagnosed 324.

FIG. 3 is a block diagram of one embodiment of the sleep analysis methodof the present invention showing, among other things, the step ofsuspecting that a patient who cannot be moved to a sleep lab has a sleepdisorder. In this embodiment, a patient cannot be moved to a sleep unitor lab, but the patient's caregiver suspects that the patient has asleep disorder 328. The patient may be unable to move to a sleep unit orlab for a variety of reasons, including but not limited to a medicalcondition such as severe cardiovascular disease or paralysis. After thepatient's caregiver suspects that the patient has a sleep disorder, aphysician, nurse, technician, or the like applies sensors to the subject332 at the patient's location. Such a location includes a hospital,nursing home, hospice, other skilled nursing facility, or the like.Before or after the sensors are applied to the patient, they areconnected to a wireless data acquisition system 336. The sleep test isthen started by collecting data while the subject attempts to sleep inthe patient's current location 340. During the test, data is collectedand wirelessly transmitted to a remote sleep unit or lab, a databaseaccessible to a remote sleep unit or lab, or a remote monitoring station344. Based on the transmitted data, a sleep analysis is performed andthe patient is diagnosed 348.

FIG. 4 is a signal flow diagram of one embodiment of the data flowthrough the wireless data acquisition system used in certain embodimentsof the present invention. The sensors generate physiological signals 22,kinetic signals 24, and environmental signals 26. The sensor signals 27interface with the wireless data acquisition system 50, consisting of(a) a patient interface box 35 containing a sensor interface module 28,a preprocessor module 30, a transceiver module 32, and a power module34, and (b) a base station 43 containing a storage module 38, a secondpre-processor module 40, and a communication module 42. Typically, thepatient interface box 35 is worn by the patient during the test period.For portability of the patient interface box 35, the power module 34 canbe battery-based. The patient interface box 35 sends data via wirelesssignal 46 to the base station 43. The base station 43 uses thecommunication module 42 to wirelessly retransmit the signals from thesensors 27 and/or transmit signals based at least in part on at leastone of the signals 27 to remote stations (not shown). Optionally,environmental signals 26 could be fed directly into the base station 43.Further optionally, all the signals 27 could be fed directly into asingle box (not shown) containing the sensor interface module 28,pre-processor module 30, storage module 38, communication module 42, andpower module 34.

FIG. 5 is schematic of the remote data acquisition device and system ofthe present invention. In FIG. 5, a wireless data acquisition system 50(shown in FIG. 4) is used to receive, filter, and optionally analyzesignals 27 (shown in FIG. 4) from sensors (not shown) on a subject (notshown). The wireless in-home data acquisition system 50 transmits asignal based, at least in part, on one or more of the signals from thesensors on the subject. The wireless data acquisition system 50transmits a signal 55 preferably in real time from the subject's home 52to a server 70 for analysis. The signal 55 is transmitted over theinternet 58 or other communication system such as satellites or othertelecommunications system. If the signal 55 is transmitted over theinternet 58, preferably the signal 55 is transmitted using a cellularcard provided by cellular providers such as for example Sprint,Cingular, AT&T, T-Mobile, Alltel, Verizon or the like. The signal 55that is transmitted over the internet 58 can be compressed to providebetter resolution or greater efficiency. The server 70 performs dataanalysis (not shown). The analyzed data 73 is then entered into adatabase 76. The analyzed data 73 in the database 76 is then accessibleand can be requested 79 and sent to multiple review stations 82 such asa sleep unit or lab located anywhere in the world for further analysisand review by clinicians, technicians, researchers, doctors and thelike.

FIG. 6 shows a diagram outlining the wireless data acquisition system inmore detail. In FIG. 6, a patient interface box 85 receives signal (notshown) from a sensor 91. This sensor 91 can be an EEG electrode (asshown) or any of the other sensors described herein or known in the art.Although one type of sensor 91 is shown, the patient interface box 85 iscapable of accepting multiple signals from multiple sensors 91. In avery simple embodiment of the present invention, the patient interfacebox 85 generates a wireless signal 94 encoded with data corresponding tothe signal from the sensor 91. The patient interface box 85 transmitsthe wireless signal 94 to base station 97. In FIG. 6, the wirelesssignal 94 is shown as radio frequency (RF). In this case, the patientinterface box 85 generates a radio frequency signal 94 by frequencymodulating a frequency carrier and transmits the radio frequency signalthrough module antenna 100. The base station 97 receives the radiofrequency signal 94 through base antenna 103, demodulates the radiofrequency signal 94, and decodes the data. It is understood that otherwireless means can be utilized with the present invention, such asinfrared and optical, for example. RF wireless transmission ispreferred. Although one module antenna 100 and one base antenna 103 areshown in this embodiment, it is understood that two or more types ofantennas can be used and are included in the present invention. Anexternal programming means 106, shown in FIG. 6 as a personal computer,contains software that is used to program the patient interface box 85and the base station 97 through data interface cable 109. The datainterface cable 109 is connected to the base station 97 by connector112. Instead of a data interface cable 109, the patient interface box 85and the base station 97 can be programmed by radio frequency (or othertype) of signals transmitted between an external programming means 106and a base station 97 and the patient interface box 85 or to anotherbase station 97. RF signals, therefore, can be both transmitted andreceived by both patient interface box 85 and base station 97. In thisevent the patient interface box 85 also includes a module receiver 133(shown on FIG. 7) while the base station 97 also includes a basetransmitter 84, in effect making both the patient interface box 85 andthe base station 97 into transceivers. In addition, the data interfacecable 109 also can be used to convey data from the base station 97 tothe external programming means 106. If a personal computer is theexternal programming means 106, it can monitor, analyze, and display thedata in addition to its programming functions. The base receiver 80 andmodule receiver 133 (shown on FIG. 7) can be any appropriate receivers,such as direct or single conversion types. The base receiver 80preferably is a double conversion superheterodyne receiver while themodule receiver 133 (shown on FIG. 7) preferably is a single conversionreceiver. Advantageously, the receiver employed will have automaticfrequency control to facilitate accurate and consistent tuning of theradio frequency signal 94 received thereby.

Referring now to FIG. 7, there is shown a block diagram of the signalprocessing module 85 with the sensor 91 and the module antenna 100. Thesignal processing module 85 comprises input means 115, analog-to-digital(A/D) means 118, a module microcontroller 121 with a nonvolatile memory,advantageously, an EEPROM 124, a module transmitter 127, a connection toremovable memory 130, a module receiver 133 and a module power supply136. Although the module antenna 100 is shown externally located fromthe signal processing module 85, it can also be incorporated therein.The module antenna 100 may be a printed spiral antenna printed on acircuit board or on the case of the signal processing module 85 or othertype of antenna. A module power supply 136 provides electrical power tothe signal processing module 85 which includes the input means 115, A/Dmeans 118, module microcontroller 121, module transmitter 127 and modulereceiver 133. Additionally the signal processing module 85 willpreferably contain an accelerometer connected to a microprocessor 139for position detection, motion detection, and motion artifactcorrection.

The input means 115 is adjustable either under control of the modulemicrocontroller 121 or by means of individually populatable componentsbased upon the specific external input 88 (i.e. signal from any sensor)characteristics and range enabling the input means 115 to accept thatspecific external input 88. For example, if the input is a 4-20 mAanalog signal, the input means 88 is programmed by the modulemicrocontroller 121 and/or populated with the components needed toaccept that range and characteristic of signals. If the inputcharacteristics change the programming and/or components changeaccordingly but the same platform circuit board design is utilized. Inother words, the same platform design is utilized notwithstanding thecharacter, range, or quantity (i.e. number of external inputs 88) [up toa predetermined limit] of the input. For example, bioelectric signalssuch as EEG, EMG, EKG, EOG, or the like have typical amplitudes of a fewmicrovolts up to a few tens of millivolts. For a given application, aspecific frequency band of interest might be from 0.1 Hz to 100 Hz,whereas another application may require measurement of signals from 20Hz to 10 kHz. Alternatively, measurement of vital signs such as bodytemperature and respiration rate may deal with signals in a range of +5volts, with a frequency content from DC (0 Hz) to 20 Hz. For othermedical applications, the information of interest may be contained inthe signal as a current, current loop sensor, or it may take the form ofresistance, impedance, capacitance, inductance, conductivity, or someother parameter. The present invention anticipates using a single devicefor measuring such widely disparate signal types and presents distincteconomic advantages, especially to small enterprises such as a medicalclinic located in a rural area, which would be empowered by thisinvention to conduct tests that would otherwise require the patienttravel to a large medical center, with all the attendant cost thereof.

A single system possesses these capabilities due to the selectivelyadaptable input means 115 and A/D means 118, the frequency-agile moduletransmitter 127 and base transmitter 116, and the programmable modulemicrocontroller 121 and EEPROM 124. One universal platform design thencan be utilized for all applications. In addition, the signal processingmodule 85 can comprise multiple copies of the input means 115 and theA/D means 118. Cost savings can be achieved by multiplexing at severaldifferent points in the input means 115 and the A/D means 118 allowinghardware to be shared among external inputs 88.

After receipt by the input means 115, the external input 88 is inputtedto the A/D means 118. The A/D means 118 converts the input to a digitalsignal 142 and conditions it. The A/D means 118 utilizes at least oneprogrammable A/D converter. This programmable A/D converter may be anAD7714 as manufactured by Analog Devices or similar. Depending upon theapplication, the input means 115 may also include at least one low noisedifferential preamp. This preamp may be an INA126 as manufactured byBurr-Brown or similar. The module microcontroller 121 can be programmedto control the input means 115 and the A/D means 118 to provide specificnumber of external inputs 88, sampling rate, filtering and gain. Theseparameters are initially configured by programming the modulemicrocontroller 121 to control the input means 115 and the A/D means 118via input communications line 145 and A/D communications line 148 basedupon the input characteristics and the particular application. Ifdifferent sensors are used, the A/D converter is reconfigured byreprogramming the module microcontroller 121. In this manner, the inputmeans 115 and the A/D means 118 can be configured to accept analoginputs of 4-20 mA, +/−5 volts, +/−15 volts or a range from +/−microvoltsto millivolts. They also can be configured to accept digital inputs fordigital applications such as detection of contact closure.

The module microcontroller 121 controls the operation of the signalprocessing module 85. In the present invention, the modulemicrocontroller 121 includes a serial EEPROM 124 but any nonvolatilememory (or volatile memory if the signal processing module remainspowered) can be used. The EEPROM 124 can also be a separate componentexternal to the module microcontroller 121. Advantageously, the modulemicrocontroller 121 may be PIC16C74A PIC16C74B or a PIC16C77 bothmanufactured by MicroChip, or an Amtel AT90S8515 or similar. The modulemicrocontroller may advantageously contain two microprocessors in seriesas shown in FIG. 7. The module microcontroller 121 is programmed by theexternal programming means 106 (shown in FIG. 6) through the connector172 or through radio frequency signal from the base station 97 (shown inFIG. 6). The same module microcontroller 121, therefore, can be utilizedfor all applications and inputs by programming it for those applicationsand inputs. If the application or inputs change, the modulemicrocontroller 121 is modified by merely reprogramming. The digitalsignal 142 is inputted to the module microcontroller 121. The modulemicrocontroller 121 formats the digital signal 142 into a digital datastream 151 encoded with the data from the digital signal 142. Thedigital data stream 151 is composed of data bytes corresponding to theencoded data and additional data bytes to provide error correction andhousekeeping functions. Advantageously, the digital data stream 151 isorganized in data packets with the appropriate error correction databytes coordinated on a per data packet basis. These packets canincorporate data from a single input channel or from several inputchannels in a single packet, or for some applications may advantageouslyinclude several temporally differing measurements of one or a pluralityof input channels in a single packet. The digital data stream 151 isused to modulate the carrier frequency generated by the transmitter 127.

The module transmitter 127 is under module microcontroller 121 control.The module transmitter 127 employs frequency synthesis to generate thecarrier frequency. In the preferred embodiment, this frequency synthesisis accomplished by a voltage controlled crystal reference oscillator anda voltage controlled oscillator in a phase lock loop circuit. Thedigital data stream 151 is used to frequency modulate the carrierfrequency resulting in the radio frequency signal 94 which is thentransmitted through the module antenna 100. The generation of thecarrier frequency is controlled by the module microcontroller 121through programming in the EEPROM 124, making the module transmitter 127frequency agile over a broad frequency spectrum. In the United Statesand Canada a preferred operating band for the carrier frequency is 902to 928 MHz. The EEPROM 124 can be programmed such that the modulemicrocontroller 121 can instruct the module transmitter 127 to generatea carrier frequency in increments between 902 to 928 MHz. as small asabout 5 to 10 kHz. In the US and other countries of the world, thecarrier frequency may be in the 902-928 MHz, Wireless Medical TelemetryBands (WMTS), 608-614 MHz, 1395-1400 MHz, or 1429-1432 MHz or otherauthorized band. This allows the system to be usable in non-NorthAmerican applications and provides additional flexibility.

The voltage controlled crystal oscillator (not shown) in the moduletransmitter 127, not only provides the reference frequency for themodule transmitter 127 but, advantageously also provides the clockfunction 154 for the module microcontroller 121 and the A/D means 118assuring that all components of the signal processing module 85 aresynchronized. An alternate design can use a plurality of referencefrequency sources where this arrangement can provide certain advantagessuch as size or power consumption in the implementation.

The module receiver 133 in the signal processing module 85 receives RFsignals from the base station 97 (shown in FIG. 6). The signals from thebase station 97 can be used to operate and control the signal processingmodule 85 by programming and reprogramming the module microprocessor 121and EEPROM 124 therein.

Referring now to FIG. 8, the base station 97 has a base antenna 103through which RF signals 94 are received. Base microcontroller 160controls the operation of the base station 97 including base receiver163, base transmitter 166, and base power supply 169. Base receiver 163receives the RF signal 94 from base antenna 103. The base receiver 163demodulates the RF signal 94 and the base microcontroller 160 removesany error correction and performs other housekeeping tasks. The data isthen downloaded through connector 112 to the external programming means106 (shown in FIG. 6) or other personal computer (PC) or datastorage/viewing device for viewing in real time, storage, or analysis,or is downloaded to removable memory of some form.

FIG. 9 is a schematic diagram of a multi-task monitoring system. In FIG.9, a patient is shown having the neurological 200, cardiac 202, muscular204, and other environmental conditions 206 measured by sensors (notshown) and input into four separate patient interface boxes 210, 212,214, and 216. In this example, each unit 210, 212, 214, and 216 canaccept up to 32 inputs. The units transmit signals 220, 222, 224, and226 at different wireless radio frequencies from their respectiveantennas 228. The signals 220, 222, 224, and 226 do not interfere witheach other because they have been manually or automatically selected toreduce interference as described earlier in the application. The signalscan be received 232 simultaneously or in some ordered fashion by theantenna 230 on the receiving unit 234. The receiving unit 234 is bothdata and electrically connected via a USB connection 236 to a mainprocessor or computer 238. The physiological signals are then processedor further processed by the computer 238, depending on whetherprocessing took place in the data acquisition units 210, 212, 214, and216. The information or data from the computer 238 can be output to amonitor 240 and/or into a data file 242.

FIG. 10 is a diagram of an artifact rejection module 250 that can beused in either the in-home data acquisition system (not shown) or acomputer or processor (not shown) linked to the data acquisition unit ofthe present invention. In FIG. 10, a subject's EEG signal 252 ispreferably continuously fed 254 into artifact rejection algorithmswithin the data acquisition unit processor. Simultaneously sensorsignals 260 from the subject's movement or motion are also fed into theartifact rejection processor so the EEG signal can be corrected 262 foreffects of abnormal or prejudicial motion by the subject. The sensorsfor determining the subject's motion are described above, but the mostpreferred is an accelerometer that is incorporated into the EEG dataacquisition unit itself.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus, itis intended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What we claim is:
 1. A sleep diagnostic system comprising: a) adatabase; b) a computer or a processor; c) a portable, wearable patientinterface box adapted to be worn on a subject during testing, theportable, wearable patient interface box comprising 1) a battery; 2) anonvolatile digital memory; 3) electronics including at least threeinput channels which are programmed to receive collected data inreal-time from at least three sensors at a remote sleep location in thenonvolatile digital memory; 4) a transceiver or a transmitter thenfurther to upload the collected data, and/or data based on the collecteddata to the database, which is part of the system, the database adaptedto operate at a first location which is different from the remote sleeplocation where the subject is tested; and 5) at least two sensorconnectors adapted to electrically connect the at least three sensorsdirectly to the at least three input channels of the portable, wearablepatient interface box; d) the at least three sensors are selected from agroup consisting of: accelerometer(s), fingertip pulse oximeter,pressure sensor, microphone, strain gauge and transducers, the at leastthree sensors adapted 1) to be applied to a finger and a torso of thesubject who will be tested during sleep while located in the remotesleep location, which is remote to a sleep analysis unit or lab; 2) tomeasure or derive at least the subject's respiratory effort, snore andblood oxygenation during testing; and 3) to be electrically hardwiredand/or releasably connected to the three input channels on the portable,wearable patient interface box worn by the subject; e) the databaseaccessible to individuals from the sleep analysis unit or lab adapted toreceive the collected data and/or data based on the collected data fromthe nonvolatile memory of the portable, wearable patient interface boxuploaded to the database through the transceiver or the transmitter onthe patient interface box; f) the computer or the processor programmedto automatically identify and quantify physiological events in one ormore of the respiratory effort, snore and blood oxygenation from thedata on the database that was transferred from the portable, wearablepatient interface box, the physiological events indicative of a sleepingdisorder, the computer or processor adapted to operate at the first or asecond location other than the remote sleep location; and g) a two-waycommunication link adapted to output the i) respiratory effort, snoreand blood oxygenation datafrom the database, ii) the identified andquantified physiological events in the data, or iii) both i) and ii) ina form adapted for a professional medical diagnosis of whether thepatient suffers from a sleep disorder.
 2. The sleep diagnostic system inclaim 1, wherein one or more of the at least three sensors are furtheradapted to measure or derive the subject's body position while sleeping.3. The sleep diagnostic system claim 2, wherein movement artifactscaused by subject movement are removed using the processor or a secondprocessor and data from the at least three sensors.
 4. The sleepdiagnostic system in claim 1, further comprising a software adapted forloading onto a cellular phone of the subject or a care provider, thesoftware further adapted to allow the cellular phone to receive from thetransceiver or transmitter of the portable, wearable patient interfacebox to transfer the collected data and/or data based on the collecteddata wirelessly to the cellular phone and to then transfer the collecteddata and/or the data based on collected data, to the database viacellular systems, internet, satellite, wired-network and/or land linesto the database.
 5. The sleep diagnostic system claim 1, wherein thecomputer or processor further includes an algorithm adapted foridentifying changes in sleep stages and calculating a respiratorydisturbance index using the collected and transferred data prior tomedical diagnosis.
 6. The sleep diagnostic system claim 5, wherein thesystem is adapted to measure or derive heart or pulse rate.
 7. The sleepdiagnostic system claim 1, wherein the snore is measured and/or derivedusing a pressure sensor or microphone.
 8. A method of remote sleepanalysis and diagnosis comprising the steps of: a) applying at leastthree sensors to a subject a first sensor being directly applied to afinger of the subject, a second sensor being applied directly to a torsoof the subject, and a third sensor being applied to the subject andapplying a portable, wearable patient interface box directly to thesubject who will be tested during sleep while located in a remote sleeplocation, which is remote to a sleep analysis unit or lab, the at leastthree sensors are sensors selected from a group consisting ofaccelerometer(s), fingertip pulse oximeter(s), rip belt(s), respiratoryeffort belt(s), pressure sensor(s), microphone(s), strain gauge(s),pressure transducer(s) and transducer(s), the at least three sensors areadapted to measure and/or derive at least the subject's air flow orsnore, respiratory effort, and blood oxygenation, the at least threesensors; being electrically and directly connected to at least threeinput channels in the portable, wearable patient interface box worn bythe subject, the portable, wearable patient interface box furthercomprising a battery; a nonvolatile digital memory; electronicsincluding the at least three input channels, which are programmed tocollect data from the at least three sensors in the nonvolatile digitalmemory; and a transceiver or a transmitter to upload the collected dataand/or data based on the collected data to a database; b) collectingdata with the electronics of the patient interface box in real-time fromthe at least three sensors from the patient located in the remote sleeplocation while the subject is attempting to sleep; c) transferring, atleast in part, the collected data and/or data based on the collecteddata to a sleep analysis unit or lab or to the database adapted tooperate at a first location other than the remote sleep location; d)analyzing one or more of the air flow or snore, the respiratory effortand blood oxygenation data transferred to the database with a computeror processor programmed to identify and quantify physiological events inthe data from the database indicative of a sleep disorder, the computeror processor adapted to operate at the first or a second location otherthan the remote sleep location; and e) further medically analyzing thei) air flow or snore, respiratory effort and blood oxygenation datatransferred to the database, ii) the physiological events identified andquantified in the data from the database, or iii) both i) and ii) by amedical professional to medically diagnose whether the patient suffersfrom a sleep disorder.
 9. The method in claim 8, wherein one or more ofthe at least three sensors measure and/or derive body position whilesleeping.
 10. The method in claim 9, further including the step ofidentifying changes in sleep stages and calculating a respiratorydisturbance index with the computer or processor using the transferreddata prior to medical diagnosis.
 11. The method in claim 10, wherein thesnore is measured and/or derived using a pressure sensor or microphone.12. The method in claim 8, further including the step of transferringcollected data and/or data based on collected data from the transceiveror transmitter wirelessly to a cell phone of the subject or of a caregiver on which a software has been loaded, the software being adapted sothat once loaded on to the subject's or the care giver's cellular phoneto then transfer data based on the transferred data received from thetransceiver or transmitter on the portable, wearable patient interfacebox to the database accessible to the medical professional through thecell phone via cellular systems, internet, satellite, wired networkand/or land lines.
 13. The method in claim 8, wherein the third sensormeasures airflow and comprises a nasal cannula or a facemask, a firstpressure sensor or pressure transducer internal to the portable,wearable patient interface box, and a first air port adapted forconnecting the nasal cannula or facemask to the first pressure sensor.14. The method in claim 13, wherein the second sensor is a respiratoryeffort belt or a rip belt.
 15. A sleep diagnostic system comprising: a)a database; b) a software adapted for loading onto a subject's or careprovider's cell phone; c) a computer or a processor; d) a portable,wearable patient interface box adapted to be worn on the subject duringtesting, the portable, wearable patient interface box comprising 1)battery; 2) a nonvolatile digital memory; 3) electronics including atleast three input channels, which are programmed to receive collecteddata in real-time from at least three sensors at a remote sleep locationin the nonvolatile digital memory; 4) a transceiver or a transmitterthen further adapted to upload the data, and/or data based on thecollected data to the software on the subject's cell phone, 5) at leasttwo sensor connectors to electrically connect the at least three sensorsdirectly to the portable, wearable patient interface box; e) the atleast three sensors are selected from a group consisting of:accelerometer(s), fingertip pulse oximeter(s), belt(s), respiratoryeffort belt(s), pressure sensor(s), microphone(s), strain gauge(s),pressure transducer(s) and transducer(s), the at least three sensorsadapted 1) to be applied to the subject, the first sensor to a fingerand the second sensor to a torso of the subject, the subject who will betested during sleep while located in the remote sleep location, which isremote to a sleep analysis unit or lab; 2) airflow or snor, respiratoryeffort, and blood oxygenation of the subject during testing; and 3) tobe electrically hardwired and/or releasably connected to the at leastthree input channels on the portable, wearable patient interface boxadapted to be worn by the subject; f) the software adapted to allow thecell phone to receive, in part, the collected data and/or data based onthe collected data transmitted from the portable, wearable patientinterface box to the cell phone and then to transfer via the software onthe cell phone data based on the collected data to the database viacellular systems, internet, satellite, wired-network and/or land lines;g) the database accessible to individuals from the sleep analysis unitor lab adapted to receive the collected data and/or data based on thecollected data from the nonvolatile memory of the portable, wearablepatient interface box uploaded to the database through the subject'scell phone; h) the computer or the processor programmed to automaticallyidentify and quantify physiological events in one or more of the airflowor snore, respiratory effort and blood oxygenation, from the data thatwas transferred from the portable, wearable patient interface box, thephysiological events indicative of a sleeping disorder, computer orprocessor adapted to operate at the first or a second location bothdifferent than the remote sleep location; and i) a two-way communicationlink adapted to output i) the respiratory effort and blood oxygenationdata from the database, ii) the identified and quantified physiologicalevents in the data, or iii) both i) and ii) in a form adapted so aprofessional medical diagnosis can be made of whether the patientsuffers from a sleep disorder.
 16. The sleep diagnostic system in claim15, wherein the sensors are further adapted to measure or derive thesubject's body position while sleeping.
 17. The sleep diagnostic systemclaim 16, wherein the computer or processor further includes analgorithm adapted for identifying changes in sleep stages andcalculating a respiratory disturbance index using the collected datathat was transferred to the database.
 18. The sleep diagnostic systemclaim 17, wherein the snore is measured and/or derived using a pressuretransducer or microphone.
 19. The sleep diagnostic system claim 15,wherein the third sensor measures airflow and comprises a nasal cannulaor a facemask, a first pressure sensor or pressure transducer internalto the portable, wearable patient interface box, and a first air portadapted for connecting the nasal cannula or acemask to the firstpressure sensor.
 20. The sleep diagnostic system claim 19, wherein thesecond sensor measures respiratory effort and comprises a respiratoryeffort belt, a second pressure sensor or pressure transducer internal tothe portable, wearable patient interface box, and a second air portadapted for connecting the respiratory effort belt to the secondpressure sensor or pressure transducer.